Threading-die.



W. J. McINTY RE & D. WEIR.

THR EADING DIE. APPLICATION FILED MAR. 3, I915.

Ll65,989. Patented Dec.28,1915.

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WILLIAM 3.,MCINTYRE AND DAVID WEIR, OF HARTFORD, CONNECTICUT, ASSIGNORSTO THE ALLEN MANUFACTURING COMPANY, OF HARTFORD, CONNECTICUT, A COR-PO-RATION OF CONNECTICUT.

THREAIDINGr-DIE.

Application fiIed March 18, 1915.

To all whom it may concern.

Be it known that we, VVILLIAM J. McIn- TYRE and DAW'D WEIR, bothcitizens of the United States, residing at I-Iartford, in the county ofHartford and State of Connecticut, have invented a new and usefulImprovement in Threading-Dies, of which the following is aspecification.

This invention relates to those devices which are provided for cuttingthreads on screw bodies, bolt rods, tubes, pipes and other cylindricalpieces of metal.

In the common form of solid, split or open threading die the chasingteeth, which cut away the metal to form the thread, usually extendcompletely through the body of the die, that is, substantially all ofthe teeth from one face of the die body to the other are utilized aschasing teeth. This is ordinarily accomplished by having the clearanceopenings, which divide the threads into segments, extend all the waythrough the body. With these dies if the stock to be threaded,especially if it is a long rod of steel, varies ever so slightly indiameter, or if one section is a little harder than another, itfrequently happens that the chasing teeth do not take hold evenly; theysometimes gouge or dig in, particularly as the teeth become dull, andconsequently the threads will not be absolutely uniform in section andthe pitch will change, for the pitch of the thread formed by thecommonly used dies depends entirely upon the pitch of the out which isbeing made so that if the cut varies the thread alters. Furthermore, thecommonly used die is inclined to. load up with chips which injure thethread when the piece being threaded is reversed and unscrewed or backedout of the die.

The object of this invention is to provide a very simple form of diewhich will eliminate the enumerated difliculties and 'cut a thread on ascrew bolt or other article,

only part way through the body, and with Specification of LettersPatent.

Patented Dec. 28, 1915.

Serial No. 15,164.

a pilot thread of the same pitch extending from the inner chasing teethto the back face of the body. This is accomplished by forming theclearance openings between the chasing teeth only part way through thebody instead of entirely through the body, as in the common form of die,and as a result the pilot thread in the die draws the screw or bolt bythe thread which is out past the chasing teeth which do the cutting witha uniform lead.

In the accompanying drawings Figure 1 shows a front view of a form ofsplit die which embodies the invention. Fig. 2 shows a section on thedotted line 22 on Fig. 1, and Fig. 3 shows a back view of the same die.Fig. a shows a front view, Fig. 5 shows a section on the dotted line 5-5on Fig. 4, and Fig. 6 shows a back view of a solid die of littledifferent shape.

The die bodies 1 shown are circular in outline and through the centerare openings 2. The walls of these openings are provided with threads ofthe desired pitch. In the form first shown clearance openings 3 are madefrom the front, part way through the die body. These clearance spacesopen into the central. threaded opening so as to, for a part of thedistance through the body, sepa rate the thread into segments. Thisforms sections of the thread into chasing teeth 4 and leaves theremainder of the thread 5 to act as a pilot or lead.

In the second form illustrated the clearance openings 6 are cut out tothe edge of the body. This leaves the chasing teeth 7 on the inner edgesof segmental portions 8 011 the front face of the die. The remainder ofthe thread forms the pilot or lead 9. The bodies may be solid, asindicated in Fig. 2, or may be split, as shown in Fig. 1. The pitch ofthe thread through the central opening is uniform, but it is desirableto have the section which forms the pilot or lead slightly larger indiameter than the section which is divided to form the chasing teeth, sothe stock will not bind in the pilot section. After the screw body orbolt rod which is being threaded reaches the pilot thread in the die itis drawn forward uni formly thereby so that the chasing teeth willcontinue to out the same amount and on exactly the same pitch, Thisinsures an absolutely uniform thread on the screw or bolt from one endto the other, regardless of any slight variation in the diameter or anychange in degree of hardness or softness of the stock.

As a screw formed with this die will have a thread of uniform pitch fromone end to the other and the thread teeth will be exactly the same, itcan be cut to fit within the tapped part with which it is to be usedcloser than is possible with the old form of die wherein the pitch islikely to vary and cause the screw to bind unless it is cut suflicientlysmall to make a somewhat loose fit with the part into which it is to bescrewed.

the chasing teeth substantially the remainder of the distance throughthe body.

2. A solid threading die having a body with a threaded opening extendingfrom one face to the other, and clearance openings extending from thefront facepart way only through the body at the sides of andcommunicating with the threaded opening, whereby a portion of the threadwill be divided into segments to provide chasing teeth and a portion ofthe thread will be continuous to provide a uniform feed for the stockout by the chasing teeth.

3. A solid threading die having segmental chasing teeth that extend partway through the body, and a continuous pilot thread that extends incontinuation of the chasing teeth substantially the remainder of thedistance through the body, said pilot thread having the same pitch asthe chasing teeth and being slightly larger in diameter.

lVM; J. MoINTYRE. DAVID WEIR. WVitnesses S. K. DIMooK, TERRY J. GHAPICopies of this patent may be obtained for five cents each, byaddressingthe .Gommissioner.of Patents,

Washington, D. C.

